The pile of crumbled debris that's left over after something breaks or collapses is rubble. Famous scenes of rubble include the fallen Twin Towers on September 11 and the remains of the Haitian capital after the 2010 earthquake.
Rubble rhymes with "bubble," but when a bubble bursts, it just dissolves into liquid, while rubble is piles of rock, concrete, brick, and other remains that are a very physical reminder of destruction. Rock slides create rubble from rocks, and natural disasters and explosions create rubble from buildings, cars, and trees. Unfortunately, rubble is usually heavy and can trap people or things beneath it, as when bodies are found in the rubble of a fire or earthquake.